Why did the site disappear from the Google index?

Question

Google

Yesterday I indexed sites through Google Webmaster, they have a link to my site, after that I noticed a jump in search results. That is, the site at first went up a couple of points in the search results, then it just stupidly disappeared. Who will tell you what's going on?
PS I used to do such indexing periodically, just this time at the bottom of the site there was a signature in the form of a link to my site.